The present invention relates to a device for dosed dispensing of a fluid medium, said device comprising a pen-like housing which has a storage chamber for accommodating the fluid medium and which has at its front end a tip in which there is provided an outlet opening for the fluid medium, and further comprising a valve element which is arranged in the front end, closes the outlet opening under the force of a spring and is arranged such that it at least partially opens the outlet opening in the event of radial pressure being applied from the outside on the front end of the housing.
Such a device is known from EP 0 256 279 A1.
The known device is what is known as a metering pen with which fluid media can be dispensed in a dosed manner.
A “fluid medium” is understood within the context of the present invention to mean flowable liquids, materials and substances of any kind, which are held in a storage chamber in a metering pen and are dispensed in a dosed manner as desired. These include, for example, refinish paints and liquid or pasty correction agents which are applied to the surfaces to be treated via an applicator, for example a brush or wick, provided in the tip of the metering pen.
Such metering pens are for example used to eliminate paint damage on motor vehicles or to repair scratches and scores on structural elements such as window frames, etc., before they are painted over.
On account of the possibly relatively long storage time of the metering pens filled with the fluid media, it is frequently necessary to remix the medium, for which purpose there is provided in the metering pen a mixing ball which ensures that the medium is mixed again when the metering pen is subjected to a shaking movement.
What is also important is the option of being able to dispense the fluid media in a dosed manner, since it is frequently the case that only small amounts of the medium are required for the work to be carried out and the applicator should not become oversaturated with the medium.
In order to make this possible, the device known from above-mentioned EP 0 256 279 A1 has a cylindrical housing in which a storage chamber for the respective liquid medium to be used is provided. At its tip, the housing has an opening which is closed by an axially movable valve element in the form of a sealing rod. At the upper end of the sealing rod there is arranged a membrane plate which is pushed forwards by a compression spring so that the sealing rod closes the outlet opening by way of its front end.
In the region of the tip, the housing is produced from an elastically deformable shell so it can be pushed in there. Pushing in the housing shell on radially opposite sides or from one side only causes the membrane plate to be bent upwards, as a result of which it moves the sealing rod likewise upwards and thus lifts the sealing element fitted at the front end of the sealing rod off the outlet opening, thereby opening an annular gap through which medium can emerge.
Disadvantages with this device are in particular the large number of parts required and also the welded connection required between the tip, which consists of the elastically deformable and therefore thin housing shell, and the rest of the housing.
It is also disadvantageous that the mixing of the medium with the aid of the mixing ball is not always ensured, because the medium that accumulates in the region of the front tip cannot move readily into the rear region, since the membrane plate causes virtually complete sealing off of the chamber in the front tip from the rear storage chamber.
A comparable device is known from U.S. Pat. No. 3,902,815 A. In this device, the outlet opening for the liquid at the tip of the housing is closed by a stem-like valve member which is pushed axially forwards by a compression spring into the closed position. In order to open the outlet opening, there are provided push buttons, which are arranged diametrically in the housing wall and when pushed together ensure via interposed leaf springs that the valve member moves axially towards the rear and opens the outlet opening.
FR 1 434 743 A1, too, describes a comparable device, in which the outlet opening is closed via an axially adjustable valve member.
The two last-discussed devices are also structurally complex and so have problems associated with assembly and with use.
US 2007/0201940 A1 discloses a liquid applicator having an applicator that is displaceable in longitudinal direction and interacts with a front end of a valve element.
DE 199 34 445 A1 discloses a device for dispensing a fluid like ink from a fluid chamber through an inner channel provided in a valve part. The valve part has a tip protruding from the fluid chamber through a further channel provided in an inwardly pointing cylindrical shank provided at a front face of the fluid chamber.
The rear end of the valve part is a cylindrical block having the same outer diameter as the shank. The inner channel terminates in lateral openings provided between the shank and the cylindrical block. By this, fluid from the fluid chamber can pass through the lateral openings into the inner channel and therefrom to the outside.
However, provided on the shank and the cylindrical block is a helical spring which separates the fluid chamber from an inner chamber surrounding the lateral openings. The coils of the helical spring are tightly compressed such that no fluid can pass from the fluid chamber into the inner chamber, so that the valve is closed.
The tip is arranged within the channel such that it can be tilted. When the tip is tilted this bulges the helical spring such that the coils are splayed apart to open a fluid passage from the fluid chamber to the inner chamber.
Thus, when the tip is at rest, the coil closes off the fluid chamber. When the tip is tilted, the coil opens fluid passages that allow flow of ink from the fluid chamber through the lateral openings and the inner channel to the outside.
In this construction, the valve element, in the meaning of the present invention, is the helical spring, although it cannot be opened by applying radial pressure to the fluid chamber.
This construction has several disadvantages. When the tip is at rest, the inner chamber is still connected via the lateral openings to the inner channel, so that over the time all fluid trapped within the inner chamber can either drop out or get dried. This, of course, cannot be accepted.
Further, as the helical spring has tightly compressed coils in order to ensure closure of the fluid chamber, a large tilting force is required to open the fluid passages between certain coils.
Still further, a sealing ring is provided in the further channel provided in the inner shank. This sealing ring surrounds the tip of the valve part and allows the tilting thereof. The further channel is in fluid communication with the fluid chamber as soon as the tip is tilted. However, tilting the tip stresses the sealing ring so that fluid may pass the sealing ring and rinse out of the fluid chamber on the outer surface of the tip. This can by no means be accepted.
Seen as a whole, this known device is unsuited for dosed application of a fluid medium in the meaning of the present application.